Magnetic Bearing Protective Layer Reduces Airgap
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Solution Overview
Problem
Magnetic bearings for rotary machines operating in corrosive or particle-laden environments face limitations due to the need for thick, non-magnetic jackets that increase the airgap, reducing load capacity and not ensuring complete contact between the jacket and rotor, while existing anti-corrosion solutions are costly and difficult to maintain.
Innovation Solution
A magnetic bearing design featuring a protective annular plug coated with a corrosion-resistant layer, allowing the use of ferromagnetic materials with optimal magnetic and mechanical properties, eliminating the need for a thick jacket and enabling a smaller airgap, with the layer being cheaper and easier to refurbish during maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick non-magnetic jacket is used to protect the stator magnetic circuit against corrosion, then corrosion protection is improved, but the airgap thickness increases and load capacity decreases
Solution Approach 1:
The patent replaces the traditional thick non-magnetic jacket with a thin protective layer (such as electroplated or vapor-deposited coating) applied directly to the stator magnetic circuit. This thin film provides sufficient corrosion protection while minimizing the increase in airgap thickness, thereby maintaining the bearing's load capacity.
Solution Approach 2:
The patent employs composite material structures where a thin protective coating (such as nickel, chromium, or ceramic layers) is applied over the ferromagnetic stator material. This composite approach combines the magnetic properties of the base material with the corrosion resistance of the protective layer, achieving both goals simultaneously without requiring a thick non-magnetic jacket.
2Reliability
If a thick non-magnetic jacket is used to ensure corrosion protection, then reliability against corrosion is improved, but the airgap increases and manufacturing precision becomes harder to control
Solution Approach 1:
By using thin protective layers instead of thick jackets, the patent reduces the variability in thickness that occurs during manufacturing. Thin films can be applied with more consistent thickness control through processes like electroplating or vapor deposition, thereby improving the precision of the final airgap dimension.
3Reliability
If specific materials with high mechanical properties are used for the jacket, then corrosion protection and shape stability are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent simplifies material selection by applying thin protective coatings to standard ferromagnetic materials rather than requiring the jacket itself to be made from specialized corrosion-resistant alloys. This approach maintains shape stability while reducing the complexity of material selection and manufacturing.
4Reliability
If a thick jacket is used to protect the coils, then corrosion protection is improved, but the airgap increases and loading capacity is significantly limited
Solution Approach 1:
The patent protects the coils by applying thin protective layers directly to the stator magnetic circuit and coil surfaces, eliminating the need for a thick jacket. This approach provides adequate coil protection against corrosion while minimizing the increase in airgap thickness, thereby preserving the bearing's loading capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the loading capacity and serviceability of magnetic bearings, reduces material requirements, and extends the bearing's lifespan by minimizing deformation, while maintaining effective corrosion protection and reducing the airgap, thus improving overall performance.
Implementation Method 1
the protective layer avoids wet CO2 corrosion damages on carbon and low alloy steels, and avoids chlorides pitting corrosion damages on stainless steel
Implementation Method 2
a magnetic bearing for a rotary machine having a rotor comprises a stator magnetic circuit secured to a stationary support device. The stator magnetic circuit comprises at least one coil and a ferromagnetic body
Data Source
AI summary
A magnetic bearing comprising a stator magnetic circuit secured to a stationary support device, the stator magnetic circuit comprising at least one coil and a ferromagnetic body placed in a protective annular support, the protective annular support leaving uncovered a surface of the ferromagnetic body and a surface of the at least one coil. The bearing also comprises at least one annular plug placed on the surface of the at least one coil which is left uncovered by the protective annular support, and the annular plug and the surface of the ferromagnetic body which is left uncovered by the protective annular support are coated by a protective layer.